Reduction of TTI bundling in view of proactive imposition of air-interface resource reservation for a device class

ABSTRACT

A method and system for controlling application of TTI bundling on a carrier on which an access node provides service, the carrier defining air-interface resources. An example method includes detecting that at least a predefined threshold number of devices of a predefined class (e.g., IoT devices) are connected with the access node on the carrier. Further, the example method includes, responsive to the detecting that at least the predefined threshold number of devices of the predefined class are connected with the access node on the carrier, proactively reserving a portion of the air-interface resources for use to serve communications between the access node and the devices of the predefined class and, in view of the proactive reserving of the portion of the air-interface resources, imposing a reduction in the application of the TTI bundling by the access node on the carrier.

BACKGROUND

A cellular wireless network typically includes a number of access nodesthat are configured to provide wireless coverage areas, such as cellsand cell sectors, in which user equipment devices (UEs) such as cellphones, tablet computers, machine-type-communication devices, trackingdevices, embedded wireless modules, and/or other wirelessly equippedcommunication devices (whether or not user operated), can operate. Eachaccess node could be coupled with a core network that providesconnectivity with various application servers and/or transport networks,such as the public switched telephone network (PSTN) and/or the Internetfor instance. With this arrangement, a UE within coverage of thecellular network could engage in air interface communication with anaccess node and could thereby communicate via the access node withvarious application servers and other entities.

Such a network could operate in accordance with a particular radioaccess technology (RAT), with communications from the access nodes toUEs defining a downlink or forward link and communications from the UEsto the access nodes defining an uplink or reverse link.

Over the years, the industry has developed various generations of RATs,in a continuous effort to increase available data rate and quality ofservice for end users. These generations have ranged from “1G,” whichused simple analog frequency modulation to facilitate basic voice-callservice, to “4G”—such as Long Term Evolution (LTE), which can facilitatemobile broadband service using technologies such as orthogonal frequencydivision multiplexing (OFDM) and multiple input multiple output (MIMO).And recently, the industry has been exploring developments in “5G” andparticularly “5G NR” (5G New Radio), which may use a scalable OFDM airinterface, advanced channel coding, massive MIMO, beamforming, and/orother features, to support higher data rates and countless applications,such as mission-critical services, enhanced mobile broadband, andmassive Internet of Things (IoT).

In accordance with the RAT, each access node could provide coverage onone or more radio frequency (RF) carriers, each of which could befrequency division duplex (FDD), defining separate frequency channelsfor downlink and uplink communication, or time division duplex (TDD),with a single frequency channel multiplexed over time between downlinkand uplink use. Each such frequency channel could be defined as aspecific range of frequency having a bandwidth and a center frequencyand thus extending from a low-end frequency to a high-end frequency.

Further, on the downlink and uplink, the air interface on each carriercould be configured in a specific manner to define physical resourcesfor carrying information (e.g., user-plane data and control-planesignaling) wirelessly between the access node and UEs.

In a non-limiting example implementation, for instance, the airinterface on each carrier could be divided over time into frames,subframes, and symbol time segments, and over frequency into subcarriersthat could be modulated to carry data. The example air interface couldthus define an array of time-frequency resource elements, with eachresource element spanning a respective symbol time segment and occupyinga respective subcarrier, and the subcarrier of each resource elementcould be modulated to carry information. Further, each subframe couldfunction as a transmission time interval (TTI), and the resourceelements in each TTI on the downlink and uplink of the example airinterface could be grouped to define physical resource blocks (PRBs)that could be allocated as needed to carry data between the access nodeand served UEs.

In addition, certain resource elements on the example air interfacecould be designated for special use. For instance, on the downlink,certain resource elements could be set aside to define a downlinkcontrol region for carrying control signaling from the access node toUEs, certain resource elements could be designated to carry broadcastsynchronization signals that UEs could detect as an indication ofcoverage on the carrier and to establish frame timing, and certainresource elements could be designated to carry a reference signal thatUEs could measure to determine coverage strength, among otherpossibilities. And on the uplink, certain resource elements could be setaside to define an uplink control region for carrying control signalingfrom UEs to the access node, and certain resource elements could bedesignated to carry uplink reference signals or the like that could beused to evaluate uplink channel conditions, among other possibilities.

OVERVIEW

When a UE enters into coverage of an example network, the UE coulddetect threshold strong coverage of an access node on a particularcarrier (e.g., a threshold strong reference signal broadcast by theaccess node on that carrier) and could then engage in random-access andconnection signaling, such as Radio Resource Control (RRC) signaling,with the access node to establish an RRC connection or the like throughwhich the access node will then serve the UE on the carrier. Further, ifthe UE is not already registered for service with the core network, theUE could transmit to the access node an attach request, which the accessnode could forward to a core-network controller for processing. And thecore-network controller could then coordinate setup for the UE of one ormore user-plane bearers extending between the UE and a core-networkgateway that provides transport-network connectivity.

Once the UE is so connected and registered, the access node could thenserve the UE in an RRC-connected mode on the carrier, managing downlinkair-interface communication of packet data to the UE and uplinkair-interface communication of packet data from the UE.

For instance, when the core-network gateway receives user-plane data fortransmission to the UE, the data could flow to the access node, and theaccess node could buffer the data, pending transmission of the data tothe UE. With the example air-interface configuration noted above, theaccess node could then allocate downlink PRBs in an upcoming TTI forcarrying at least a portion of the data, defining a transport block, tothe UE. And the access node could then transmit to the UE in thedownlink control channel of that TTI a Downlink Control Information(DCI) message that designates the allocated PRBs, and the access nodecould accordingly transmit the transport block to the UE in thosedesignated PRBs.

Likewise, on the uplink, when the UE has user-plane data fortransmission on the transport network, the UE could buffer the data,pending transmission of the data to the access node, and the UE couldtransmit to the access node a scheduling request that carries a bufferstatus report (BSR) indicating the quantity of data that the UE hasbuffered for transmission. With the example air-interface configurationnoted above, the access node could then allocate uplink PRBs in anupcoming TTI to carry a transport block of the data from the UE andcould transmit to the UE, in the downlink channel of a preceding TTI, aDCI message that designates those upcoming PRBs. And the UE could thenaccordingly transmit the transport block to the access node in thedesignated PRBs.

This process could be used to facilitate various types of communicationby various types of UEs. For example, the process could enablewirelessly-equipped smart phones and other computing devices to engagein general Internet communications as well as packet-based real-timemedia communications such as voice over Internet Protocol (VoIP)communication, streaming video communication, and gaming, among otherpossibilities. Further, the process could enable communication by IoTdevices such as Cat-M1, narrowband IoT (NB-IoT), or other low power(e.g., low power wide area network (LPWAN)) machine-type-communication(MTC) (e.g., enhanced MTC (eMTC)) and/or machine-to-machine (M2M)devices, among other possibilities.

In a representative system, to help ensure successful air-interfacetransmission between the access node and a served UE (on the downlinkand/or uplink), the access node and UE could be configured to apply anautomatic retransmission process, such as a Hybrid Automatic RepeatRequest (HARD) process.

With HARQ, after a transmitting entity has transmitted a block of datato a receiving entity, possibly together with forward-error-correctioncoding, the transmitting entity waits to receive a HARQ response fromthe receiving entity, based on the receiving entity's evaluation ofwhether the data arrived successfully (e.g., based on a cyclicredundancy check (CRC)). If the transmitting entity receives a positiveacknowledgement (ACK) as the HARQ response, then no re-transmission isneeded and the transmitting entity can proceed to transmit additionaldata. Whereas, if the transmitting entity receives a negativeacknowledgement (NACK) as the HARQ response, then the transmittingentity re-transmits the data, possibly with different error-correctioncoding. Further, the transmitting entity may also re-transmit the dataif the transmitting entity does not receive any HARQ response within acertain period of time.

This re-transmission approach can allow data to be successfully decodedby the receiving entity even when there is a substantial probabilitythat the transmitted data would be received with one or more errors, forexample, because of poor radio frequency (RF) conditions. Specifically,the data can be re-transmitted multiple times (e.g., up to a setre-transmission limit), possibly with varying error-correction coding,until the receiving entity can decode the data without errors.

This re-transmission approach, however, also increases latency. Forexample, for each re-transmission, there can be a period of delaybetween when the transmitting entity transmits data and when thetransmitting data receives a NACK response from the receiving entity,and there can be another period of delay between when the transmittingentity receives the NACK response and when the transmitting entity thenre-transmits the data. This latency issue could be especially troublingfor latency-sensitive communications, such as VOID communication orother packet-based real-time media communications.

In order to reduce the delay associated with re-transmitting data, therepresentative system could also be configured to support a bundlingoption for data transmissions. For instance, while scheduledtransmission of a transport block may normally occur in just one TTI andthe transmitting entity may then wait to receive a HARQ response beforere-transmitting the transport block or proceeding to transmit anothertransport block, the system could allow for TTI bundling.

With TTI bundling, the transmitting entity would automatically transmita block of data repeatedly in multiple (e.g., consecutive) TTIs defininga TTI bundle, and the receiving entity would then provide a HARQresponsive for that set of transmissions cooperatively rather thanproviding a separate HARQ response after each transmission. After thetransmitting entity provides the transmissions repeatedly in themultiple TTIs, the transmitting entity would then wait to receive a HARQresponse for that group of transmissions as a whole—i.e., a HARQresponse indicating whether or not the receiving entity successfullyreceived the block of data.

This TTI bundling process could allow for more robust reception of data,without the delay that would be associated with the transmitting entitytransmitting the data multiple times and waiting for a HARQ responserespectively after each transmission.

Unfortunately, however, communication using TTI bundling necessarilyalso consumes a number of PRBs or other such resources on the accessnode's air interface that might not otherwise be consumed without use ofTTI bundling. For instance, if transmission of a block of data wouldnormally occur in six PRBs of a TTI, and if TTI bundling would involveautomatically engaging in that transmission four times, thencommunicating that block of data using TTI bundling would necessarilyconsume twenty-four PRBs—even if the first, second, or third of thosetransmissions is successful.

Normally, this extra consumption of air-interface resources may betolerable, as a trade-off for helping to reduce latency.

However, another technical problem that can arise in an example systemis that the access node may sometimes operate with a set of its PRBsproactively reserved for use to carry communications for a particularclass of UEs. That proactive resource reservation could further limitPRB availability on the air-interface and, when combined with use of TTIbundling, could be troubling.

For instance, to help ensure that air-interface capacity exists to serveIoT devices (e.g., eMTC, NB-IoT, and/or Cat-M1 devices), the access nodemight be configured to detect when at least a predefined thresholdnumber of IoT devices are RRC connected with the access node on a givencarrier and, in response, to proactively reserve a set of PRBs on thatcarrier for use to carry air-interface communications with those IoTdevices. This PRB reservation would be proactive, in anticipation of alikely future need to schedule air-interface communications to/from theconnected IoT devices, and is therefore distinct from reactivelyreserving PRBs to carry data that is currently waiting to betransmitted.

An example such PRB-reservation could be a reservation of one or morespecifically designated PRBs on a per-TTI basis or the like, such as agroup of PRBs (contiguous or non-contiguous) at the same designatedfrequency position(s) respectively in each TTI or one or more designatedTTIs per frame. Or the reservation could be with respect to certainpercentage or number of such PRBs per unit time even if not at the samefrequency position per TTI. Other examples are possible as well.

Once the access node proactively imposes this example resourcereservation in response to at least the predefined threshold number ofIoT devices being connected with the access node on the carrier,resource availability on that carrier would necessarily become morelimited. Especially at times of heavy usage, this reducedresource-availability could then pose an issue for timely scheduling oflatency-sensitive communications or other communications on the carrier.

The present disclosure provides a mechanism to help address this issue.In accordance with the disclosure, once the access node proactivelyimposes an air-interface resource reservation on a carrier, for instancein response to at least a predefined threshold number of UEs of a givenclass being connected with the access node on the carrier, the accessnode will then reconfigure itself to reduce the extent of TTI bundlingthat the access node applies on the carrier, with the reconfigurationheling to mitigate the reduced resource-availability on the carrier.

In an example implementation, for instance, the access node mightnormally be configured to schedule use of TTI bundling on the carrierfor VoIP communication as noted above (e.g., to schedule use of TTIbundling for a communication in response to the communication being VoIPcommunication). But in response to the access node proactively imposingan air-interface resource reservation on the carrier due to at least apredefined threshold number of UEs of a given class being connected withthe access node on the carrier, the access node could dynamicallyreconfigure itself to not schedule use of TTI bundling on the carrierfor VoIP communication (e.g., to not schedule use of TTI bundling for acommunication even though the communication is VoIP communication).Further, the access node could maintain this revised configurationtemporarily, such as until the number of connected UEs of the givenclass devices drops to below the threshold for instance, and the accessnode could then revert to its default configuration.

Alternatively, in another example implementation, the access node mightnormally be configured to schedule use of TTI bundling on the carrierwith use of a particular TTI bundling factor defining the quantity oftransmissions in each bundle. And in response to the access nodeproactively imposing the air-interface resource reservation on thecarrier due to at least a predefined threshold number of UEs of a givenclass being connected with the access node on the carrier, the accessnode could then dynamically reconfigure itself to reduce the TTIbundling factor, i.e., to reduce the quantity of transmissions in eachbundle. For instance, the access node could reconfigure itself from adefault mode of operation in which the access node schedules TTIbundling with a bundling factor of four (e.g., an initial transmissionand three automatic retransmissions) to a revised mode of operation inwhich the access node schedules TTI bundling with a bundling factor ofthree (e.g., an initial transmission and two automatic retransmissions).

Moreover, in this implementation, the access node could base the levelof reduction of the TTI bundling factor and/or the resulting configuredTTI bundling factor on the size of the resource reservation (e.g., theabsolute or percentage number of PRBs proactively reserved per TTI orotherwise per unit time) that the access node proactively imposes and/oron one or more other factors. For instance, if the access nodeproactively imposes a relatively large resource reservation on thecarrier, then the access node might responsively apply a largerTTI-bundle-size reduction, and if the access node proactively imposes arelatively small resource reservation on the carrier, then the accessnode might responsively apply a smaller TTI-bundle-size reduction.

These as well as other aspects, advantages, and alternatives will becomeapparent to those of ordinary skill in the art by reading the followingdetailed description, with reference where appropriate to theaccompanying drawings. Further, it should be understood that thedescriptions provided in this overview and below are intended toillustrate the invention by way of example only and not by way oflimitation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram of an example network arrangementin which features of the present disclosure can be implemented.

FIG. 2 is a flow chart depicting an example method in accordance withthe present disclosure.

FIG. 3 is a simplified block diagram of an example computing systemoperable in accordance with the present disclosure.

FIG. 4 is a simplified block diagram of an example access node operablein accordance with the present disclosure.

DETAILED DESCRIPTION

An example implementation will now be described in the context of asystem operating according to 4G LTE or 5G NR by way of example. Itshould be understood, however, that the principles disclosed hereincould extend to apply with respect to other RATs as well. Further, itshould be understood that other variations from the specificarrangements and processes described are possible. For instance, variousdescribed entities, connections, functions, and other elements could beadded, omitted, distributed, re-located, re-ordered, combined, orchanged in other ways. In addition, it will be understood that technicaloperations disclosed as being carried out by one or more entities couldbe carried out at least in part by a processing unit programmed to carryout the operations or to cause one or more other entities to carry outthe operations.

Referring to the drawings, as noted above, FIG. 1 is a simplified blockdiagram of an example wireless communication system in which features ofthe present disclosure can be implemented. In particular, FIG. 1 depictsa representative network that functions primarily to serve UEs withwireless packet data communication service, including possiblyvoice-over-packet service, but may also provide other functions.

As shown, the network includes an example access node 12, which could bea 4G LTE access node (e.g., evolved Node-B (eNB)) or a 5G NR access node(e.g., next generation Node-B (gNB)), among other possibilities.

This access node could be a macro access node of the type configured toprovide a wide a range of coverage or could take other forms, such as asmall cell access node, a relay node, a femtocell access node, or thelike, possibly configured to provide a smaller range of coverage.Further, the access node could be configured to provide coverage on atleast one carrier 14, which could be FDD or TDD as discussed above.

In an example implementation, the air interface on this carrier could beconfigured to define various air-interface resources for carryingcommunications between the access node and UEs.

By way of example, in the time domain, the air interface could define acontinuum of 10-millisecond (ms) frames, each divided into ten 1-mssubframes as TTIs, and each TTI could be further divided into a numberof timeslots, each additionally divided into symbol time segments. Andin the frequency domain, the bandwidth of the carrier could be dividedinto subcarriers with specified subcarrier spacing on the order of 15 to240 kHz. With this example arrangement, the air interface would definethe array of resource elements as noted above, with each resourceelement spanning a respective symbol time segment and occupying arespective subcarrier, and the access node and UEs could communicatewith each other through modulation of the subcarriers to carry data inthose resource elements.

Further, particular sets of resource elements on the air interface couldbe grouped together to define the PRBs discussed above. In an exampleimplementation, each PRB could span one timeslot in the time domain anda group of subcarriers in the frequency domain. Depending on the carrierbandwidth, the air interface could thus support a certain finite numberof such PRBs across the bandwidth of the carrier within each TTI.

In addition, certain resource elements on the downlink and uplink of theexample air interface could be designated for particular use asdiscussed above.

For instance, on the downlink, certain resource elements per TTI coulddefine a downlink control region for carrying control signaling such asscheduling directives and HARQ messaging from the access node to UEs.And other resource elements per TTI could define a shared channel inwhich the access node could allocate PRBs on an as-needed basis to carrydata communications from the access node to UEs. Further, resourceelements distributed in a predefined pattern throughout the carrierbandwidth per TTI could carry a broadcast reference signal as notedabove, which UEs could measure as a basis to evaluate coverage strengthand quality and to provide channel estimates to facilitate precoding,beamforming, or the like.

In addition, in certain downlink subframes, a group of resource elementscentered on the center frequency of the carrier in certain TTIs couldcarry the broadcast synchronization signals noted above, which UEs coulddetect as a way to discover coverage of the access node on the carrierand to establish frame timing. And in certain downlink subframes, agroup of resource elements also centered on the center frequency of thecarrier in certain TTIs could carry broadcast system informationmessages, such as a master information block (MIB) and systeminformation block (SIB) messages that UEs could read to obtainoperational parameters such as carrier bandwidth (e.g., downlinkbandwidth and/or uplink bandwidth) and other information.

On the uplink, on the other hand, certain resource elements per TTI,such as sets of PRBs at the low-frequency end of the carrier and at thehigh-frequency end of the carrier, could define an uplink control regionfor carrying control signaling such as access requests, channel-qualityreports, scheduling requests, and HARQ messaging, from UEs to the accessnode. And other resource elements per TTI could define a shared channelin which the access node could allocate PRBs on an as-needed basis tocarry data communications from UEs to the access node. Further, stillother resources on the uplink could be used for other purposes as well,such as to carry uplink reference signals or the like.

In the example of FIG. 1, the access node is shown interconnected with acore network 16 that provides connectivity with a transport network 18.The core network 16 could be a packet-switched network configured as anEvolved Packet Core (EPC) network or a Next Generation Core (NGC) corenetwork, among other possibilities, with entities having InternetProtocol (IP) addresses and being configured to communicate with eachother through virtual packet-tunnels or the like.

In an example EPC arrangement, as shown, the core network 16 includes aserving gateway (SGW) 20 and a packet-data-network gateway (PGW) 22, forcarrying user-plane communications through the core network 16 betweenthe access node 12 and the transport network 18. Further, the corenetwork 16 includes a mobility management entity (MME) 24, whichfunctions as a core-network controller, responsible for managing UEattachment and bearer setup, among other operations, and a homesubscriber server (HSS) 26, which stores UE profile records and mayspecify service-subscription plans, UE device type and configuration,and/or other such UE profile information.

The example core network 16 is also shown including an elementmanagement system (EMS) 28, which could operate as a central repositoryof operational data for the wireless communication network and tocontrol and manage operation of various network elements, to help ensureoptimal use of their resources. In practice, entities such as the accessnode 12 could regularly report to the EMS 28 various operational data,such as data regarding connectivity and service of UEs, and dataregarding access node load (e.g., PRB utilization) and performance,among others. And the EMS 28 could oversee operation of the access node12 and other entities, providing operation directives or the like towhich the entities could be configured to respond accordingly.

In addition, as further shown, the core network 16 and/or transportnetwork 18 in the example arrangement could include or provideconnectivity with an example Internet Multimedia Subsystem (IMS) 30. TheIMS 30 could include various proxy servers and media servers configuredto provide packet-based real-time media services, such as VoIP-callservices for served UEs. For instance, to facilitate VoIP-call service,a UE served by access node 30 might engage in packet-based call-setupsignaling, such as Session Initiation Protocol (SIP) signaling, with theIMS 30 to establish a packet-based real-time media session that extendsbetween the UE and the IMS 30 via the access node 12 and the corenetwork 16, and the IMS 30 might establish a connection with a remotecall party and bridge that connection with the UE's packet-basedreal-time media session, so that the UE and remote party could thenengage in voice-call communication.

For representative VoIP communication, voice could digitized and encodedusing a codec that might encode and output voice frames of 20milliseconds each or so. The encoded data could then be packetized andtransmitted to the other end, where the data could be de-packetized,decoded, and played out. Thus, as a UE is engaged in a VoIP call, asequence of voice packets could pass respectively in each direction toand from the UE, carrying voice communications respectively in eachdirection.

FIG. 1 depicts multiple example UEs 32 that may be within coverage ofand connect with access node 12 from time to time. These UEs could be ofvarious types, including for instance any of the types noted above,among other possibilities.

When each such UE initially enters into coverage of the system, the UEcould discover threshold strong coverage of access node 12 and, as notedabove, could then engage in random-access and connection signaling, toestablish an RRC connection with the access node 12, thus putting the UEin an RRC connected mode. Further, the UE could engage in attachsignaling through the access node 12 with the MME 24. And afterauthentication of the UE and/or at other times during service of the UE,the MME 24 could coordinate setup for the UE of one or more user-planebearers each including a radio-access bearer (RAB) that has a data radiobearer (DRB) extending over the air between the access node 12 and theUE and an S1-U tunnel extending between the access node 12 and the SGW20, and including an S5 tunnel extending between the SGW 20 and the PGW22. In addition, the access node 12 could establish for the UE a contextrecord, indicating the UE's connected state and identifying each suchbearer configured for the UE, and could report the UE connection data tothe EMS 28.

In relation to this attachment process or at another time, the accessnode 12 could also obtain configuration and capabilities data regardingthe UE, such as data indicating the UE device type (e.g., whether thedevice is an IoT device or rather a consumer device such as a cellphone) and service subscription details (e.g., whether the devicesupports VoIP-call communication, etc.), and could store this data inthe UE context record for reference while serving the UE. For instance,during the attachment process, the MME 24 could obtain this data fromthe HSS 26 and could covey the data to the access node 12 for storage,and/or the UE could provide the access node 12 with a report of thisdata. Further, the EMS 28 could also have access to this data regardingthe UE, perhaps obtaining the data from the HSS 26 or access node 12,among other possibilities.

Each bearer that the MME 24 sets up for the UE could have acorresponding quality of service class indicator (QCI) level, whichcould indicate a class or type of communication that would be carried bythe bearer, and which the access node 12 could note in its contextrecord for the UE connection.

For instance, upon initial attachment, the MME might set up for the UE abest-efforts general Internet bearer (e.g., QCI 8 or 9) for use to carrygeneral Internet communications. And if the UE is a particular type ofdevice, such as an IoT device, the MME 24 might set up a bearer with aQCI level deemed appropriate for that type of UE (e.g., QCI 7). Further,if the UE subscribes to VoIP service, the MME 24 might set up for the UEan IMS-signaling bearer (e.g., QCI 5) for carrying SIP signaling betweenthe UE and the IMS. And if and when a VoIP call is set up for the UE,the MME 24 might set up for the UE a dedicated VoIP bearer (e.g., QCI1). Other examples are possible as well.

Once the UE is so connected with an access node 12 and attached, asnoted above, the access node 12 could then serve the UE.

For instance, when the access node 12 receives data destined to the UE,the access node 12 could allocate downlink PRBs of an upcoming TTI tocarry a block of that data to the UE and, in the downlink control regionof that upcoming TTI could transmit to the UE a DCI message designatingthe allocated PRBs of that TTI. And the access node 12 could accordinglytransmit the block of data to the UE in the allocated PRBs of that TTI.The UE might then determine if the UE successfully receives thescheduled transmission (e.g., based on a CRC analysis) and, as notedabove, then transmit to the access node 12 either an ACK, which wouldsignal successful completion of the transmission, or a NACK, which maycause the access node 12 to engage in retransmission.

Alternatively, the access node 12 could apply TTI bundling for thisdownlink transmission to the UE. For instance, the access node couldallocate downlink PRBs of each of a series of upcoming TTIs to carryrespective transmissions of the block of data to the UE, perhaps eachwith different error-correction coding, and the access node couldtransmit to the UE a DCI message that designates the TTI bundling factorand allocated PRBs per TTI. The access node 12 could then accordinglyengage in the multiple transmissions to the UE. And based on whether theUE successfully receives the block of data through these multipletransmissions from the access node, the UE could then transmit to theaccess node 12 either an ACK or NACK.

Likewise, when the UE has data to transmit, UE could send a schedulingrequest to the access node, the access node could allocate uplink PRBsof an upcoming TTI to carry a block of the data from UE and couldtransmit to the UE a DCI message designating the allocated PRBs of theupcoming TTI, and the UE could accordingly transmit the block of data tothe access node 12 in the allocated PRBs of that TTI. The access node 12might then determine if the access node successfully receives thescheduled transmission (e.g., based on a CRC analysis) and, as notedabove, then transmit to the UE either an ACK, which would signalsuccessful completion of the transmission, or a NACK, which may causethe UE to engage in retransmission.

Alternatively, for this uplink transmission from the UE, the access node12 might similarly apply TTI bundling. For instance, the access nodecould allocate uplink PRBs of each of a series of upcoming TTIs to carryrespective transmissions of the block of data from the UE, perhaps eachwith different error-correction coding, and access node could transmitto the UE a DCI message that designates the TTI bundling factor andallocated PRBs per TTI. The UE could then accordingly engage in themultiple transmissions to the access node 12. And based on whether theaccess node 12 successfully receives the block of data through thesemultiple transmissions from the UE, the access node 12 could thentransmit to the UE either an ACK or NACK.

In an example implementation, the access node 12 could have a defaultconfiguration and thus default mode of operation in which the accessnode 12 is configured to apply TTI bundling for a given communicationbased on the communication type, among other possible factors. Forinstance, the access node 12 could be provisioned with data thatspecifies various communication types as to which the access node 12 isto automatically apply TTI bundling and/or various types ofcommunications as to which the access node 12 is to not apply TTIbundling.

Example communication types as to which the access node 12 could be soconfigured to apply TTI bundling might include VoIP communication andother latency-sensitive communications. Whereas, example communicationtypes as to which the access node could be so configured to not applyTTI bundling might include best-efforts communications such as generalInternet communications for instance.

With this default configuration, if and when the access node 12 isserving a VoIP communication (e.g., as indicated by the communicationbeing on a QCI-1 bearer or when deep packet inspection or other analysisso indicates), the access node 12 could automatically apply TTI bundlingto the communication. Whereas, if and when the access node 12 is servinga best-efforts communication (e.g., as indicated by the communicationbeing on a QCI-9 bearer or when deep packet inspection or other analysisso indicates), the access node 12 could automatically not apply TTIbundling to the communication.

As further indicated, the access node 12 could also be configured toproactively reserve some of the PRBs of carrier 14 in response to theaccess node 12 detecting that at least a predefined threshold highnumber of UEs of a particular type are RRC connected with access node12. This could be on the downlink and/or the uplink.

For instance, the access node 12 might be configured to proactivelyreserve some of the PRBs of the carrier 14 for use to serve Cat-M1 IoTdevices in response to the access node 12 determining that at least apredefined threshold high number of Cat-M1 IoT devices are currentlyRRC-connected with the access node 12. This predefined threshold highnumber could be set by engineering design and/or business policy to be anumber where it would be important or useful to help ensure that therewill be sufficient PRB availability for use to serve such devices.Further, the threshold could be predefined to vary per time of dayand/or based on consideration of one or more other factors, such as load(e.g., PRB utilization) on the carrier, among other possibilities. Andthe device type at issue could be a particular class of devices that isdefined in advance to be at issue.

As an example implementation of this process, assume that carrier 14defines 100 PRBs per TTI. In a default mode of operation, the accessnode 12 might not have a portion of those PRBs proactively reserved foruse to carry communications with Cat-M1 devices.

Upon determining that the number of Cat-M1 devices currentlyRRC-connected with the access node 12 has risen to the predefinedthreshold number, the access node 12 could then reconfigure itself fromthe default mode of operation to a mode of operation in which the accessnode 12 has a portion of the PRBs proactively reserved for use to carrycommunications with Cat-M1 devices. For instance, the access node 12might designate 8 PRBs per TTI as PRBs reserved for use to carrycommunications with the Cat-M1 device and may record this proactiveresource reservation in its internal memory or other data storage forreference when it later becomes necessary to schedule communicationswith the connected Cat-M1 devices. With this proactive resourcereservation, the access node 12 may then more likely and readilyschedule communications with Cat-M1 devices when necessary.

As noted above, however, this proactive resource reservation could alsocontribute to reduced PRB availability for other UEs served by theaccess node 12.

In line with the discussion above, to help address this issue, when theaccess node 12 proactively imposes this or another such resourcereservation on the carrier, the access node 12 could responsively alsoreconfigure itself to reduce the access node's application of TTIbundling on the carrier.

For instance, the access node 12 could responsively reconfigure itselffrom (i) a default mode of operation where the access node 12 wouldautomatically apply TTI bundling in response to particular TTI-bundlingtriggers such as communication type to (ii) a revised mode of operationin which the access node 12 would not apply TTI bundling in response tosuch triggers. Or the access node 12 could responsively reconfigureitself from (i) a default mode of operation in which, when the accessnode 12 applies TTI bundling, the access node would apply the TTIbundling with a first TTI-bundling factor to (ii) a revised mode ofoperation in which, when the access node 12 applies TTI bundling, theaccess node 12 would apply the TTI bundling with a second TTI-bundlingfactor that defines a smaller bundle, with less automatic repeattransmission, than the first TTI-bundling factor.

In an example implementation, the access node 12 could so reconfigureitself by setting a flag or other configuration setting in its internalmemory or other data storage specifying the reconfigured state ofoperation. For instance, the access node 12 might normally have a storedsetting indicating that the access node 12 is to apply TTI bundling whenthe communication type at issue is VoIP communication. But in responseto the access node 12 proactively imposing a PRB reservation for Cat-M1devices in view of the access node 12 having at least a threshold highnumber of RRC-connected Cat-M1 devices, the access node 12 could clearthat stored setting or change the stored setting to no longer indicatethat the access node 12 is to apply TTI bundling when the communicationtype at issue is VoIP communication

In accordance with the default setting, the access node 12 would thusapply TTI bundling when the communication type at issue is VoIPcommunication. But then in accordance with the revised setting, theaccess node 12 would not apply TTI bundling when the communication typeat issue is VoIP communication.

Similar processing could apply to cause a reduction in TTI-bundlingfactor rather than disabling TTI bundling. And as noted above, theaccess node 12 could base the extent of its reduction in TTI-bundlingfactor on various considerations. For instance, the access node 12 couldbase the extent of its reduction in TTI-bundling factor on the size ofits proactive PRB reservation. In addition or alternatively, the accessnode 12 could base the extent of its reduction in TTI-bundling factor onan evaluation of load, such as PRB-utilization (e.g., percentage of PRBsallocated per unit time) on the carrier 14, perhaps reducing theTTI-bundling factor more when the carrier is more highly loaded and lesswhen the carrier is less highly loaded.

When the access node imposes such a reduction in application of TTIbundling in response to the access node proactively imposing theresource reservation due to having a threshold high number of connectedUEs of a particular class, the access node 12 could impose the reductionin application of TTI bundling generally for all UEs served by theaccess node 12 or just for specific UEs or in specific situations. Forexample, the access node could impose the reduction in TTI bundling forUEs of a relatively low service-level class and/or only when carrier 14has at least a predefined high level of load, among other possibilities.

Further, as noted above, when the access node 12 has applied thisreduction in its application of TTI bundling, the access node 12 couldkeep the reduction in place temporarily and could automatically revertto its default mode of operation in response to one or more reversiontriggers. For example, the access node 12 could automatically revert toits default mode of operation when the number of RRC-connected devicesof the class at issue drops to below (e.g., sufficiently below) thepredefined threshold level, as a result of UEs transitioning to RRC-idlemode or otherwise disconnecting from the access node 12, among otherpossibilities.

Note also that, while various operations have been described so far asbeing carried out by the access node 12, various such operations couldbe coordinated and/or carried out by one or more other entities. By wayof example, in the arrangement of FIG. 1, the EMS 28 might coordinatethe disclosed process. For instance, the EMS 28 might learn, fromreports from access node 12 or the like, when the access node has atleast the predefined threshold high number of RRC-connected UEs of theclass at issue, and the EMS 28 might responsively transmit to the accessnode 12 a signaling message to which the access node 12 is configured torespond by proactively imposing an associated PRB reservation and, perthe present disclosure, therefore also transitioning to reduce theextent of TTI-bundling that the access node is configured to apply.

FIG. 2 is a flow chart depicting a method that could be carried out inaccordance with the present disclosure, to control application of TTIbundling on an RF carrier on which an access node provides wirelesscommunication service, where the carrier defines air-interface resources(e.g., PRBs), and where the access node supports application of TTIbundling on the carrier. For instance, the access node could be accessnode 12 as described above, configured by default to apply TTI bundlingfor certain types of communications. And the method could be carried outby the access node and/or carried out or otherwise coordinated by anexternal computing system such as the EMS 28 discussed above.

As shown in FIG. 2, at block 34, the method includes detecting that atleast a predefined threshold number of devices of a predefined class areconnected with the access node on the carrier. And at block 36, themethod includes, responsive to the detecting that at least thepredefined threshold number of devices of the predefined class areconnected with the access node on the carrier, (i) proactively reservinga portion of the air-interface resources for use to serve communicationsbetween the access node and the devices of the predefined class and (ii)in view of (e.g., in response to) the proactive reserving of the portionof the air-interface resources, imposing a reduction in the applicationof the TTI bundling by the access node on the carrier.

In line with the discussion above, the predefined class of devices couldbe IoT devices or a particular type of IoT devices, among otherpossibilities.

In line with the discussion above, the reduction in the application ofthe TTI bundling by the access node could additionally be based on adetermination that the carrier has at least a predefined threshold highlevel of load. For instance, the access node could impose the reductionin the application of the TTI bundling in view of the proactive resourcereservation being made and there being at least a predefined thresholdhigh level of PRB utilization on the carrier.

Further, as discussed above, the imposing of the reduction in theapplication of the TTI bundling by the access node could take variousforms.

For instance, it could involve reconfiguring the access node from (i) afirst mode in which the access node is configured to apply the TTIbundling in response to a TTI-bundling trigger (e.g., the communicationat issue being VoIP communication) to (ii) a second mode in which theaccess node is not configured to apply TTI bundling in response to theTTI-bundling trigger.

Alternatively or additionally, it could involve reconfiguring the accessnode from (i) a first mode in which, when the access node applies TTIbundling, the access node applies the TTI bundling with a first bundlingfactor defining a first quantity of repeated transmissions per block ofdata to (ii) a second mode in which, when the access node applies TTIbundling, the access node applies the TTI bundling with a secondbundling factor that defines a second quantity of repeated transmissionsper block of data, the second quantity being less than the firstquantity. And in this case, the method could also include setting anextent of the reduction based on a size of the portion of theair-interfaces proactively reserved.

Still further, as discussed above, the method could additionallyinclude, responsive to a reversion trigger, undoing the imposedreduction in the application of the TTI bundling. And the reversiontrigger could include detecting that fewer than the predefined thresholdnumber of devices of the predefined class are connected with the accessnode on the carrier.

FIG. 3 is next a simplified block diagram of an example computing systemthat could carry out various features as described above, to controlapplication of TT bundling on an RF carrier on which an access nodeprovides wireless communication service, where the carrier definesair-interface resources, and where the access node supports applicationof TTI bundling on the carrier. As noted above, this computing systemcould be the EMS 28, among other possibilities.

As shown in FIG. 3, the example computing system includes a networkcommunication interface 38, a processing unit 40, and non-transitorydata storage 42, which could be integrated or communicatively linkedtogether by a system bus, network, or other connection mechanism 44.

The network communication interface 38 could comprise a wired orwireless network communication module, such as an Ethernet interface,through which the computing system can communicate with other entities.And the processing unit 40 could comprise one or more processors, suchas one or more general purpose processors (e.g., microprocessors) and/orspecialized processors (e.g., application specific integrated circuits).

Further, the non-transitory data storage 42 could comprise one or morevolatile and/or non-volatile storage components, such as magnetic,optical, or flash storage media. And as shown, the data storage 42 couldhold, store, encode, or otherwise embody program instructions 46. In arepresentative implementation, those program instructions 46 could beexecutable by the processing unit 40 to carry out various featuresdescribed herein such as those described with respect to FIG. 2 forinstance.

Finally, FIG. 4 is a simplified block diagram of an example access node,such as access node 12 discussed above for instance, operable inaccordance with the present disclosure to control application of TTIbundling on an RF carrier on which the access node provides wirelesscommunication service, where the carrier defines air-interfaceresources, and where the access node supports application of TTIbundling on the carrier.

As shown, the example access node includes a wireless communicationinterface 48, a backhaul communication interface 50, and a controller52, which could be integrated together in various ways and/orinterconnected by a system bus, network, or other communicationmechanism 54 as shown.

The wireless communication interface 48 could include a radio andantenna structure through which the first access node could beconfigured to communicate with and serve UEs on the carrier. And thebackhaul communication interface 50 could comprise a wired or wirelessnetwork communication module, such as an Ethernet interface, throughwhich to communicate with other entities, such as entities on or via acore network.

Further, the controller 52 could comprise a processing unit (e.g., oneor more processing units such as microprocessors and/or specializedprocessors), non-transitory data storage (e.g., one or more volatileand/or non-volatile storage components, such as magnetic, optical, orflash storage), and program instructions stored in the data storage andexecutable by the processing unit to carry out (e.g., cause the accessnode to carry out) various operations as described herein.

Various features discussed above can be implemented in this context aswell, and vice versa.

Further, the present disclosure contemplates a computer-readable mediumencoded with, storing, or otherwise embodying program instructionsexecutable by a processing unit to carry out various operationsdescribed herein.

Exemplary embodiments have been described above. Those skilled in theart will understand, however, that changes and modifications may be madeto these embodiments without departing from the true scope and spirit ofthe invention.

We claim:
 1. A method for controlling application of transmission timeinterval (TTI) bundling on a radio-frequency (RF) carrier on which anaccess node provides wireless communication service, wherein the carrierdefines air-interface resources, and wherein the access node supportsapplication of TTI bundling on the carrier, the method comprising:detecting that at least a predefined threshold number of devices of apredefined class are connected with the access node on the carrier; andresponsive to the detecting that at least the predefined thresholdnumber of devices of the predefined class are connected with the accessnode on the carrier, (i) proactively reserving a portion of theair-interface resources for use to serve communications between theaccess node and the devices of the predefined class and (ii) in view ofthe proactive reserving of the portion of the air-interface resources,imposing a reduction in the application of the TTI bundling by theaccess node on the carrier.
 2. The method of claim 1, wherein the methodis carried out by the access node.
 3. The method of claim 1, wherein themethod is coordinated by a computing system that is in networkcommunication with the access node.
 4. The method of claim 1, whereinthe devices of the predefined class are Internet-of-Things (IoT)devices.
 5. The method of claim 1, wherein the reduction in theapplication of the TTI bundling by the access node is additionally basedon a determination that the carrier has at least a predefined thresholdhigh level of load.
 6. The method of claim 1, wherein imposing thereduction in the application of the TTI bundling by the access nodecomprises reconfiguring the access node from (i) a first mode in whichthe access node is configured to apply the TTI bundling in response to aTTI-bundling trigger to (ii) a second mode in which the access node isnot configured to apply TTI bundling in response to the TTI-bundlingtrigger.
 7. The method of claim 1, wherein imposing the reduction in theapplication of the TTI bundling by the access node comprisesreconfiguring the access node from (i) a first mode in which the accessnode is configured to apply the TTI bundling to voice over InternetProtocol (VoIP) communication to (ii) a second mode in which the accessnode is not configured to apply TTI bundling to VoIP communication. 8.The method of claim 1, wherein imposing the reduction in the applicationof TTI bundling by the access node comprises reconfiguring the accessnode from (i) a first mode in which, when the access node applies TTIbundling, the access node applies the TTI bundling with a first bundlingfactor defining a first quantity of repeated transmissions per block ofdata to (ii) a second mode in which, when the access node applies TTIbundling, the access node applies the TTI bundling with a secondbundling factor that defines a second quantity of repeated transmissionsper block of data, the second quantity being less than the firstquantity.
 9. The method of claim 8, further comprising setting an extentof the reduction based on a size of the portion of the air-interfacesproactively reserved.
 10. The method of claim 1, further comprising,responsive to a reversion trigger, undoing the imposed reduction in theapplication of the TTI bundling.
 11. The method of claim 1, wherein thereversion trigger comprises detecting that fewer than the predefinedthreshold number of devices of the predefined class are connected withthe access node on the carrier.
 12. A computing system operable tocontrol application of transmission time interval (TTI) bundling on aradio-frequency (RF) carrier on which an access node provides wirelesscommunication service, wherein the carrier defines air-interfaceresources, and wherein the access node supports application of TTIbundling on the carrier, the computing system comprising: a networkcommunication interface; a one processing unit; non-transitory datastorage; and program instructions stored in the non-transitory datastorage and executable by the processing unit to carry out operationsincluding: detecting that at least a predefined threshold number ofdevices of a predefined class are connected with the access node on thecarrier, and responsive to the detecting that at least the predefinedthreshold number of devices of a predefined class are connected with theaccess node on the carrier, causing the access node (i) to proactivelyreserve a portion of the air-interface resources for use to servecommunications between the access node and the devices of the predefinedclass and (ii) in view of the proactive reserving of the portion of theair-interface resources, to impose a reduction in the application of theTTI bundling by the access node on the carrier.
 13. An access nodeoperable to control application of transmission time interval (TTI)bundling on a radio-frequency (RF) carrier on which the access nodeprovides wireless communication service, wherein the carrier definesair-interface resources, and wherein the access node supportsapplication of TTI bundling on the carrier, the access node comprising:a wireless communication interface including an antenna structurethrough which the access node is configured to communicate on thecarrier; and a controller configured to carry out operations to controlthe application of the TTI bundling on the carrier, wherein theoperations include detecting that at least a predefined threshold numberof devices of a predefined class are connected with the access node onthe carrier, and wherein the operations include, responsive to thedetecting that at least the predefined threshold number of devices ofthe predefined class are connected with the access node on the carrier,(i) proactively reserving a portion of the air-interface resources foruse to serve communications between the access node and the devices ofthe predefined class and (ii) in view of the proactive reserving of theportion of the air-interface resources, imposing a reduction in theapplication of the TTI bundling by the access node on the carrier. 14.The access node of claim 13, wherein the controller comprises aprocessing unit, non-transitory data storage, and program instructionsstored in non-transitory data storage and executable by the processingunit to carry out the operations.
 15. The access node of claim 13,wherein the reduction in the application of the TTI bundling by theaccess node is additionally based on a determination that the carrierhas at least a predefined threshold high level of load.
 16. The accessnode of claim 13, wherein imposing the reduction in the application ofthe TTI bundling by the access node comprises reconfiguring the accessnode from (i) a first mode in which the access node is configured toapply the TTI bundling in response to a TTI-bundling trigger to (ii) asecond mode in which the access node is not configured to apply TTIbundling in response to the TTI-bundling trigger.
 17. The access node ofclaim 13, wherein imposing the reduction in the application of TTIbundling by the access node comprises reconfiguring the access node from(i) a first mode in which, when the access node applies TTI bundling,the access node applies the TTI bundling with a first bundling factordefining a first quantity of repeated transmissions per block of data to(ii) a second mode in which, when the access node applies TTI bundling,the access node applies the TTI bundling with a second bundling factorthat defines a second quantity of repeated transmissions per block ofdata, the second quantity being less than the first quantity.
 18. Theaccess node of claim 17, wherein the operations further include settingan extent of the reduction based on a size of the portion of theair-interfaces proactively reserved.
 19. The access node of claim 13,wherein the operations further include, responsive to a reversiontrigger, undoing the imposed reduction in the application of the TTIbundling.
 20. The access node of claim 13, wherein the devices of thepredefined class are Internet-of-Things (IoT) devices.